Thousands of scientists strive to identify cellular mechanisms that can lead to breakthroughs in the development of ameliorative treatments for debilitating neural and muscular conditions such as spinal cord injury, stroke, Parkinson's disease, Huntingtons disease, ALS and Multiple Sclerosis. Most studies use rodent models to test hypotheses, and these studies are all limited by the methods available to evaluate animal motor function. To continue to make advancements in developing treatments for these debilitating conditions, there is a critical need for more sensitive, repeatable, and time efficient methods for quantifying functional movements in an open field environment. The goal of this project is to fill this critical need by developing a method to automatically quantify and classify gross 3D movements and stepping kinematics in the open field for multiple animals simultaneously, without placing markers on the animals or requiring hand digitization. State of the art 3D volumetric reconstruction techniques will be used to measure and classify characteristic movements of uninjured and injured mice, and anatomical landmark tracking algorithms will quantify stepping coordination. Open field evaluations of motor performance allow a wide variety of behaviors to be analyzed and testing of multiple animals simultaneously, which will significantly reduce the time needed for evaluation. The markerless measurement and motor function evaluation technique will be developed and tested by classifying spinal cord injury (SCI) severity in mice. These animals display extremely challenging motor dysfunction that ranges from complete paralysis to normal locomotion. Assessment methods which are effective for murine SCI would likely generalize to larger rodents like rats and to other disease states where motor deficits are less severe. To make the method accessible to researchers, the number of cameras, data capture rates and trial lengths needed to accurately quantify and classify open field behavior will be minimized. This proposal will develop, refine and optimize this markerless approach for evaluating motor function by accomplishing the following specific aims: (1) Automatically identify clinically relevant 3D movements in the open field which reflect motor impairments of different severities using center of volume measurements and can be measured for multiple animals simultaneously. (2) Relate disease severity to patterns of fore- and hindlimb coordination in the open field. This approach is innovative because it will apply markerless motion tracking algorithms, which have been primarily developed for humans, to questions related to mouse motor function. This will give researchers access to quantitative measures of animal motion that have never been possible before. This approach can produce significant and fundamental changes in behavioral movement assessments since it will combine all of the most powerful features of current state-of-the art motor function assessments. The result would be an automated method that produces accurate, sensitive, repeatable measurements of open-field movements for use in quantitative evaluations of motor performance.